Only the police tape, the bloodstain on the ground and a grotesque mystery remained Sunday after the brutal attack on the MacArthur Causeway in which one naked man was shot dead by police after he attacked another naked man and began eating his face.

Drivers coming back from Miami Beach on the causeway took their feet off the gas, bike riders slowed down and dog walkers stopped to look at the scene of Saturday afternoon’s macabre assault, which generated international headlines.

They didn’t see much. The scene had been cleaned up

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Security video from the adjacent Miami Herald building captured snippets of the violence on the MacArthur’s off-ramp to Biscayne Boulevard as the two men — one dead, the other gravely injured — lay on the sidewalk as scores of officers arrived.

The victim remained Sunday at Jackson Memorial Hospital’s Ryder Trauma Center. In addition to eating the man’s flesh, his attacker, according to police sources, tried to gouge out his eyes. Neither was identified Sunday, and the name of the officer who killed the attacker was not released.

But that didn’t stop people from talking, wondering and offering up their own theories.

Police said it all began about 2 p.m. Saturday when a Road Ranger spotted the men and shouted on his loudspeaker for the attacker to back away. Meanwhile, a woman also saw what was happening flagged down an officer.

One witness, Larry Vega, told WSVN-Fox 7 he was riding his bicycle on the MacArthur when he saw a man tearing off pieces of the victim’s flesh with his mouth.

“I told him to get off,” Vega told the station, “and the guy just kept eating the other guy away.”

Vega said he found a police officer, who approached and told the attacker to get off the man.

“The guy just stood, his head up like that, with pieces of flesh in his mouth,” Vega said. “And he growled.”

The officer fired, striking the attacker, but the man kept chewing, Vega said. The officer fired again, hitting him several more times, eventually killing him.

After that, Vega said, all he saw was blood.

“It’s one of the most gruesome things I’ve ever seen in my life in person,” he told the station.

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Under the causeway’s bridge Sunday, in the area near the attack populated by homeless people, a sheltered space was littered with cardboard mats, syringes and broken bottles. A man who called himself “Rio” stood near the off-ramp, about 100 feet from the crime scene, holding a sign that read “homeless please help.”

Rio said he wasn’t the only person who hung around the area. But Saturday, when he was there, he didn’t see anyone else. He was napping, Rio said, when the chaos began.

“A police officer woke me up and told me I was in the middle of a crime scene,” Rio said.

On the other side of the causeway, near the eastbound lanes, another man who gave only his first name, Andres, was returning to his usual spot after showering and having a warm meal at a Miami church, he said.

“In my experience, I don’t see crack or anything like that around here,” he said.

But drugs remained part of the conversation. Saturday, police theorized that the attacker might have suffered from “cocaine psychosis,” a drug-induced craze that bakes the body internally and often leads those it affects to strip naked to try to cool off.

Other theories abounded, of course, sometimes leading to comparisons to one horror-movie staple, zombies.

And though it may have happened in Miami, others elsewhere weighed in.

Sean Newell wrote on the popular sports blog, Deadspin: “This kind of crazy only happens in Florida.”